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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 0 |
| 5 | 1 |
| 6 | 2 |
| 7 | 3 |
| 8 | 8 |
| 9 | 25 |
| 10 | 116 |
| 11 | 1253 |
| 12 | 30334 |
| 13 | 3161239 |
| 14 | 2890534072 |
| 15 | 37908199848897 |
| 16 | 39946852159641845000 |
| 17 | 25587984997105954864555102857 |
| 18 | 56071032677809871004962669691748664133130 |
[-1,0,1,0,1,2,3,8,25,116,1253,30334,3161239, 2890534072,37908199848897,39946852159641845000, 25587984997105954864555102857, 56071032677809871004962669691748664133130] |